The major goal of this application is to maintain the Specific Pathogen Free (SPF) program at the Caribbean Primate Research Center's (CPRC) through support of operations, management, veterinary care, virological and MHC typing, and by the improvement of the comprehensive genetic management plan. A unique feature of the CPRC animals that had facilitated the successful establishment and improved sustainability of the SPF colony is that these animals are naturally free of SIV and SRV-D, two of the four viruses to be tested for(4). Undoubtedly, this trait has contributed to the establishment of a successful program with very limited number of sero-conversions. Nevertheless, for safety and as required for the SPF Program, The CPRC continues systematically testing for all four viruses (B virus, STLV, SIV and SRV-D). The Program provides unadmixed Indian-origin rhesus monkeys with defined genetic and virological background. The population genetic analyses revealed that the SPF colony has remained genetically homogenous over time with sufficient amounts of heterozygosity and minima stratification from its non- SPF founders. Genetic variation will be maintained in the SPF colony using the genetic management strategies described in this application. The genetic management approach will allow for enrichment of desired MHC markers in demand for biomedical research while maintaining genetic diversity. To ensure the long-term viability of the CPRC-SPF colony, the Center's approach for genetic management will be concordant with the NIH's National NHP Genetics and Genomics Working Group's guidelines. The estimate of Indian ancestry among the C P R C - S P F a n i m a l s is also among the highest that have been calculated across several National Primate Research Centers (NPRCs) in the US. Funds are requested in this application to maintain the SPF program and to meet the proposed aims. With continued NIH support, the Institutional contribution and with funds from the program income, the SPF program at CPRC will remain a significant national research resource and will be able to provide healthy SPF Indian- origin rhesus monkeys of defined genetic and virological background to NIH-sponsored research programs, specially HIV/AIDS studies.